Add Class#hierarchy and Class#lineage

[Fryguy]

@bdunne Please review. See specs for examples.

I frequently need this in order to understand a given OO class hierarchy or lineage, so this is probably mostly for diagnostic usage, but useful nonetheless.

require 'socket'

IO.hierarchy
# => {BasicSocket=>
#      {Socket=>{},
#       IPSocket=>{TCPSocket=>{TCPServer=>{}}, UDPSocket=>{}},
#       UNIXSocket=>{UNIXServer=>{}}},
#     File=>{}}

TCPServer.lineage
# => [TCPSocket, IPSocket, BasicSocket, IO, Object, BasicObject]

[miq-bot]

Checked commit Fryguy@8f5358f with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
4 files checked, 0 offenses detected
Everything looks fine. 🍰